Amount of amortization expense attributable to debt issuance costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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-Section S99
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-Subparagraph (SX 210.5-03(8))
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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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Amount, before accumulated amortization, of debt issuance costs related to line of credit arrangements. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section S45
-Paragraph 1
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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Debt - Debt Issuance Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 6.4	$ 5.6	$ 4.5
Senior Secured Revolving Credit Facility \| Line of Credit \| ABL Credit Facility and Notes
Debt Instrument [Line Items]
Debt issuance costs	41.5
Amortization of debt issuance costs	6.3	$ 3.4
Senior Secured Revolving Credit Facility \| Long-term Debt \| Line of Credit \| ABL Credit Facility and Notes
Debt Instrument [Line Items]
Debt issuance costs	22.5
Senior Secured Revolving Credit Facility \| Other long-term assets \| Line of Credit \| ABL Credit Facility and Notes
Debt Instrument [Line Items]
Debt issuance costs in assets	$ 19.0